1. Field of the Invention
The present invention relates to an apparatus and a method for establishing an information path, and more particularly, in a synchronous digital hierarchy (SDH) system.
2. Background of the Related Art
Generally, a synchronous digital hierarchy (hereinafter abbreviated SDH) system in accordance with the ITU-T suggestion produces synchronous transfer module (STM) n rank signal by processing DS-1, DS-2, and DS-3 rank signals in a T1 signal system or DS-1E, DS-2E, DS-3E, and DS-4E rank signals in an E1 signal system according to a predetermined hierarchy.
In order to transfer a predetermined asynchronous signal through the SDH system, a series of procedures for converting the corresponding asynchronous signal into an STM-n signal of a synchronous transfer module have to be carried out. Namely, the SDH system accommodates an asynchronous DS rank signal of the T1 or E1 system in a container, forms a virtual container (VC) by attaching a path overhead (POH) to the corresponding container, forms a tributary unit (TU) signal by attaching a pointer byte and a justification bit to the virtual container (VC), and forms a tributary unit group (TUG) signal by multiplexing the TU signal. Then, an administration unit group (AUG) and an STM-n signal are formed successively by carrying out additional processing on the TUG signal.
The present invention relates to realizing a TU-m pointer-processor application specific integrated circuit (ASIC) that processes the TU-m (m=11, 12, 2, 3) rank signals as the TU signals, which is compared to the following related art.
When interpreting and producing a TU-m rank pointer, a multiplexing path of an AUG signal of the AUG is selected by a setup of a microprocessor. Processing of the TU-m rank pointer is carried out along the selected path.
FIG. 1 illustrates a path for a general TU-m rank pointer processing. An AUG signal is demultiplexed into AU-4 or AU-3 signal and then pointer-processed. Thereby, the AUG signal is aligned into a VC-4 or a VC-3 signal, respectively. The demultiplexing/multiplexing processing of the AU-4 signal is carried out along a path such as AU-4→VC-4→TUG-3→VC-3→TU-3→TUG-3 and the like, while demultiplexing/multiplexing processing of the AU-3 signal is carried out along a path such as AU-3→VC-3→TUG-2→TU-2(TU-11, TU-12)→VC-2(VC-11, VC-12)→TU-2(TU-11, TU-12) →TUG-2 and the like. In this case, available paths for processing the respective signals are established variously.
An ASIC for carrying out pointer processing along such paths includes a pointer interpretation unit interpreting a pointer, a pointer generation unit producing the pointer, and a microprocessor interface monitoring and controlling the pointer interpretation and generation. Such a construction of an ASIC is well-known in the art and its description will be skipped.
An operator determines a path for the pointer processing in the related art. Namely, the operator, selects a path for processing a pointer in a plurality of paths and then establishes the microprocessor construction for the selected path. As a result, a multiplexing path of the AUG signal of the administration unit group is selected by the selection of the microprocessor construction, whereby the interpretation and generation of the TU-m rank pointer is achieved along the selected path.
As the multiplexing construction of the conventional AUG signal is achieved by the constructional establishment of the microprocessor, path establishment by the operator should precede the established construction. Therefore, the operator has to select a pointer processing path for interpretation and generation of the TU-m rank pointer by himself in the related art. Specifically, system operational efficiency is reduced since the operator does the path establishment.
Besides, a multiplexing/demultiplexing path for pointer processing, as shown in FIG. 1, is constructed as a mirror image, for instance, centering around VC-C. Therefore, when the operator selects a path to be processed and establishes a microprocessor construction to fit the selected path, unnecessary software has to be added to the same path.
The above reference is incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.